When God created man, called him and said: - Man, I have a good and bad news for you. The man replied: - Lord, give me the good news first! And God said: - When I created, did away with two very important organs: a head and a penis. The man then asked: - But then, Sir, what's the bad news? God replied: - Blood is little, so only work one at a time ...

I hope you find one that can have blood in the two ... at the same time.